Monday, April 30, 2007

Reply to John Loftus on the AFRJohn Loftus wrote: Anyway, Vic, I believe the Euthyphro dilemna applies to Logic as well as Goodness. Did God create the rules of logic, or must he follow them? Do you have anything to add to this latter dilemna that you haven't said about the former dilemna?

It's probably not unlike Godel's theorem when it comes to math. We can use math effectively, but it cannot yield information concerning both the completeness and consistency of the mathematical system itself. So we must refer to metamathematical statements to explain the system. Now, either there are such things as metamathematical statements which explain the whole system, or there are not, but whether they exist is left undecided by the system itself.

I reply:John: I need to go over the structure of the AFR again to help understand how it is supposed to go. The argument begins by examining the necessary conditions of rational inference: such things as the intentionality required for propositional attitudes, truth and falsity, mental causation in virtue of content, logical laws and their psychological relevance, personal identity throughout the rational inference, and the reliability of our rational faculties. My claim is that if any of these is missing, then we do not make rational inferences. We then look at what kinds of properties and causes there can be if naturalism is true. We look at the natural world, as understood by physics, and ask whether these necessary conditions can occur in a universe in which all there is is, at bottom, physical. The “physical” is defined in such a way that the basic stuff of the universe is not rational, not intentional, etc. and all causation is supposed to by physical causation. The laws governing that stuff are not the laws of logic, they are the laws of physics, and if the physical stuff comes into a “rational” configuration it happens to be that way because of what physical configurations obtain. What we call “rational thought” has to be a systemic byproduct of an essentially non-rational nature, and on my view there is something very, very, paradoxical about asserting something like this.

Now if someone wanted to define materialism widely enough so that something whose essence it was to perceive logical truths could be a material thing, then I guess I could even qualify as a materialist. But if we did that we would be straying big-time from our ordinary conception of “matter.” However, so long as we are not trying to call something “matter,” then it is perfectly possible for non-material things to be able to perceive logical relations as part of their essence. So God can be an essentially rational being, who knows all the logical truths in all possible worlds. Whereas we cannot say of a piece of matter that it is essentially rational without stretching the concept of matter beyond all recognition, we can say of God that God is essentially rational, and it fits perfectly with our ordinary understanding of God.Link

28 Comments:

Suppose we make a rational argument for some conclusion, C. The argument contains a set of premises, P1, P2, P3...PN.

In any argument relevant to our rational faculties, one might be tempted to claim that, since P1-PN contain no explicit guarantee of rational capacity, one ought not have confidence in the conclusion of the argument, because we cannot trust our faculties to have followed the argument in the first place.

However, implicit in every rational argument is an initial premise, P0, which says that we assume that we are rational and that the problem under study is amenable to rational analysis. That is, P0 assumes axioms of rationality, including logical consistency, induction, and the axiomatic nature of our experiences.

Without this implicit premise, no rational arguments would work.

There's a simple way of stating this result. We cannot have a rational argument for the axioms of rationality. Any such argument would rely on the axioms it was trying to prove.

That means that any supposed rational argument that states that God guarantees our rationality (and a world where such faculties are applicable) is circular. In order to find such a rational argument persuasive, I would first have to assume that I am rational in order to prove that I am rational.

Implicitly, a naturalistic argument about origins incorporates P0. If a theist later says "ah, but your argument must make the additional assumption that the naturalistic process made us rational," then the theist would find that this line of argument was ineffective. The original argument, like all rational arguments, assumed we were rational in step zero, so it costs us nothing to reassert this assumption later.

Likewise, any rational argument we make that refers to God also incorporates P0. That means we are immune from atheists asking questions like "how do you know God isn't just making you think you're rational?"

This doesn't mean we cannot critique a rational argument on the grounds that it contradicts the rational faculties upon which it relies. However, in order to use this approach, we have to show that P1-PN truly contradict P0. We have to show that the premises that follow P0 make rationality totally impossible. Accusing an argument of not making all of rationality explicit is not adequate to invalidate the argument.

Indeed, the AfR does exactly what the last paragraph above says, it specifies an outright conflict not merely an explanatory gap. One way to appreciate this is that under closure of the physical, premises P1 - PN must be physical objects/events/states. However, premises simply don't have properties that can be identified with physical entitities. Even if premises supervene on physical entities, then the causal relations between premises are still actually causal relations between physical properties--which directly contradicts the necessity that causation in logical though must be in virtue of the non-physical properties of premises. Assuming that some of our thought sequences are logical, they must be caused by non-physical properties of premises.

We cannot reach a conclusion rationally and at the same time reach it for reasons other than those we perceive; to assert the contrary is incoherent with rationality as we experience it.

...which directly contradicts the necessity that causation in logical thought must be in virtue of the non-physical properties of premises.

I think the demand for "non-physical properties of premises" is question-begging.

What is it we know about the premises in the first place? We know that a premise refers to a set of potential experiences consistent with the premise. If experience supervenes on the physical, then so do the potential experiences.

In order for me to think the proposition "all men are mortal," I need a model of men and mortality. This model correlates past observations of men with past observations of mortality in some predictive way. This model has to be mechanistic.

At the same time, the truth of the model is to be found in the later experiences of its predictions. That verification is also mechanistic.

If I have a mechanism that implements this premise, I can combine it with another similar mechanisms which implement other premises.

So, here's a mechanistic system that refers to potential experiences in the same way that a rational argument would. It is possible for a mechanistic system to fail to do this, but I see no proof here that a mechanistic system cannot do this.

>>What is it we know about the premises in the first place? We know that a premise refers to a set of potential experiences consistent with the premise. If experience supervenes on the physical, then so do the potential experiences<<

Telling us what it is premises refer to does not tell us what, in the physical sense, premises are. Nor does claiming that potential experiences supervene on the physical--a highly problematic statement all by itself.

This is pretty simple. Under causal closure of the physical, we must identify a premise with something physical in order for it to do causal work in a physical system. The trouble is, whatever we are tempted to identify as a premise turns out to be a representation of a premise. "All men are mortal" as lines on paper or on a computer screen is a representation of a premise, not the premise itself. The same goes for electrical impulses in electronic circuitry. But representation is not identity. Moreover, the representation relation is weaker than supervenience: representation and referent need not covary out of logical or metaphysical necessity (referent here being the premise represented by the artifact, not the object of the premise). Therefore the physical properties of a representation may not be identified as the properties of the referent. Therefore causal work done by such physical properties cannot be claimed to have been done by the referent.

>>This model correlates past observations of men with past observations of mortality in some predictive way. This model has to be mechanistic.<<

Assuming that you are identifying the premise with a model, the model cannot be mechanistic. If it were mechanistic you could conceivably present it to me as the object of sensory observation, either directly or by means of scientific instruments. But you cannot present the "model"/premise itself to me. You can present me with an artifact that represents the model/premise, or possibly with a neural firing sequence that correlates with it. I don't believe sensory contact with a premise as opposed to a representation can even be conceived. Contact with a premise is purely introspective, not sensory, although it may be prompted in a mysterious way (from a naturalistic standpoint) by sensory contact with a representation.

Under causal closure of the physical, we must identify a premise with something physical in order for it to do causal work in a physical system. The trouble is, whatever we are tempted to identify as a premise turns out to be a representation of a premise.

You are asking how we ought to define the meaning of a proposition. And, of course, a representation of a proposition is not the same as its meaning.

Well the answer to this question has been around since the 1930's. The meaning of a proposition is its method of verification or falsification. There are variations on this theme, including logical positivism and Bayesian philosophy. If I give you a representation of a proposition, you only know what it means when you know what its implications are, either for other propositions ( i.e., computationally) or for future experience.

Therefore the physical properties of a representation may not be identified as the properties of the referent. Therefore causal work done by such physical properties cannot be claimed to have been done by the referent.

I find this rather puzzling. When I consider the proposition "2+2=4", the axioms of arithmetic are not "doing work." My mind is doing work by exploring the terrain of the timeless logical relation. As my mind does the exploring, it either faithfully explores the terrain, or it fails to do so.

We use premises in abstract arguments that refer to things which presently may or may not exist physically. For example, I could construct a model of stellar evolution that's hypothetical, and which generates predictions that will turn out to be wrong. However, fixing the axioms of the theory (and the background information as I believe it to be), always leads to the same conclusion in a time dependent way. It doesn't matter whether I adopt those premises now or in the deep future, the rational conclusion is the same. So, it is not the case that the premises are doing work, because otherwise the assembly of arguments and the finding of conclusions would be instantaneous.

But you cannot present the "model"/premise itself to me. You can present me with an artifact that represents the model/premise, or possibly with a neural firing sequence that correlates with it.

This gets back to my original point about meaning. Suppose I give you some symbols that purport to be a meaningful premise. How do you translate them? You need to create a theory of their meaning, and correlate that theory with other theories that you have tested in the past. You find a best theory of meaning and understand it in terms of consequences for your experience.

As I see it, your argument relies on the premise that meaning is magical (that the meaning of a proposition is just magically known by the receiver).

However, we have many reasons to believe that this is not the case. We know that meaning is learned, and that we develop theories about the meanings of newly encountered words in our native language.

Furthermore, intentionality fits very well into a physicalist theory. A contemporary computer doesn't understand the text that I am writing because it does not know how to act (or what to expect) on the basis of the representations. It does not know how to create a theory about their meaning, nor how to test that theory.

However, any machine that can establish theories of meaning would be capable of understanding what we write. A machine that takes input, seeks out models of that input, and makes predictions about future inputs would be capable of understanding representations of propositions about those inputs.

>The meaning of a proposition is its method of verification or falsification.<

I don't think you mean exactly this. Take the proposition, "There are eggs in my refrigerator." The method of verifying this proposition is to go to my refrigerator. But the meaning of the proposition is not my going to my refrigerator.

>There are variations on this theme, including logical positivism and Bayesian philosophy. If I give you a representation of a proposition, you only know what it means when you know what its implications are,<

You seem here to be identifying a proposition with its verifiable implications. That doesn't work. Take the proposition, "The First World War began in 1914." I can check on the truth or falsehood by going to encyclopedias, books, looking at historical monuments, etc. But the proposition in question is not the same as the proposition, "There exist evidences that the First World War began in 1914." Nor is it the same as those evidences themselves. Nor is it even the physical occurrence of the war in 1914; the beginning of the war came and went but the proposition may be present now.

>I find this rather puzzling. When I consider the proposition "2+2=4", the axioms of arithmetic are not "doing work." My mind is doing work by exploring the terrain of the timeless logical relation. As my mind does the exploring, it either faithfully explores the terrain, or it fails to do so.<

To adopt your metaphor, when you explore the terrain you interact with its features, which is another way of saying that the features of the terrain do causal work. A hill causes me to climb or else to alter my course in some way to avoid climbing because the hill has real causal influence. Likewise, if my brain is interacting with the proposition that 2+2=4, then the proposition must have causally potent features to interact with. But if the features of the proposition are not physical, then there cannot be physical interaction of my brain with those features--at least, there cannot be in the mechanical sense in which we ordinarily understand "physical interaction."

The fact that mental processes are time-dependent is not enough to qualify them as physical cause-and-effect sequences. The causal relations of such sequences must be understood in terms of physical properties other than mere temporality. There must be sensory accessibility, either directly or by means of scientific instruments. And the properties that make physical cause-effect sequences available to the senses must be the same type of properties that govern their mutual interaction. The molecular electromagnetic repulsion that causes one clock gear to impart motion to another gear is relatable to the light reflecting off both gears that enables me to see their interaction. To repeat, logical relations are introspectively "seen" in a way that does not fit into a sense-accessible physical picture. That is why we intuitively recognize the words "seen" and "grasped" as metaphors when used with regard to mental objects.

>As I see it, your argument relies on the premise that meaning is magical (that the meaning of a proposition is just magically known by the receiver).<

"Magical" implies a lack of intelligibility--events that occur without rhyme or reason. That is certainly not the case with apprehension of the meanings of propositions such as premises. Why I am saying is that rational thought is not intelligible in physical, mechanical terms. It is intelligible in mental terms, and we must therefore demarcate the mental from the physical. If the demarcation seems somewhat mysterious, so be it.

>However, any machine that can establish theories of meaning would be capable of understanding what we write.<

And just what mechanical operation of a computer constitutes an establishment of a theory of meaning? Is it the output of certain representations, such as sentences, that we might take to refer to theories of meaning? Or is it a function that can only be imagined to be available introspectively to the computer? If the former, computers can do that now. If the latter, we have a genuine problem for physicalism.

Take the proposition, "There are eggs in my refrigerator." The method of verifying this proposition is to go to my refrigerator. But the meaning of the proposition is not my going to my refrigerator.

That's a very narrow view of verification. Sending someone else to fetch said cold eggs and their returning with them is also a form of verification. As is the expectation that, if you left the fridge unattended and inaccessible for a long time, there would be rotten eggs in the fridge. There are numerous ways to verify the claim, some of them using historical inferences. All those things you expect to experience as a consequence of there being eggs in the fridge also form your understanding of the meaning of the proposition.

Maybe I should have said it this way. The meaning of a proposition consists in all the relevant experiences regarded as consistent or inconsistent with the proposition.

(Since you cannot generally imagine all possible experiences correspondent to a claim, meaning has some uncertainty. If I say bananas are sweet and yellow, and I later discover a mauve, sour banana, I would be challenged in my meanings. I would have to revise either the definition of banana or revise my proposition because I failed to anticipate this discovery.)

Take the proposition, "The First World War began in 1914." I can check on the truth or falsehood by going to encyclopedias, books, looking at historical monuments, etc. But the proposition in question is not the same as the proposition, "There exist evidences that the First World War began in 1914."

True, but the first proposition refers to a model that is consistent with your second proposition. It does not refer to anything beyond the model and its consequences. Should you discover sufficient evidence, you could learn that the war did not begin in 1914. In that case, you would have discovered that the model did not fit your observations and experiences. Yet, the model retains its integrity, even when falsified. We can imagine a model in which the war began in 1915. It's just that this model is either false or fictional because the evidence and our experiences are inconsistent with the model.

That the war is long gone is irrelevant because the repercussions of the war are still with us. History is concerned with those actual repercussions. It is about creating models such that what we observe is "as if" we are witnessing repercussions of the events in the model.

But if the features of the proposition are not physical, then there cannot be physical interaction of my brain with those features--at least, there cannot be in the mechanical sense in which we ordinarily understand "physical interaction."

I don't think anyone takes the world to be physical in the sense you are seeing it. Rather, the belief is that the world of experience is described by natural laws or regularities. Mathematics is just such a regularity. If you move symbols around according to fixed rules (axioms), you consistently get the same results (theorems). Now, you may say that theorems are not physical, and, from a narrow perspective, they are not. However, they are natural as much as gravity is natural. And they are discoverable through computation in much the same way as physical results are discoverable. The main difference being that mathematical experiments are perfectly controlled, and have almost unlimited precision.

This being the case, minds explore mathematical landscapes no differently than they explore physical ones. If you establish a set of physical conditions, certain results reliably follow. If you establish a set of mathematical conditions, certain results reliably follow.

Mathematics does not reduce to physics, but that doesn't make mathematics supernatural. It may make it non-physical, but that's not a useful distinction, IMO.

And just what mechanical operation of a computer constitutes an establishment of a theory of meaning? Is it the output of certain representations, such as sentences, that we might take to refer to theories of meaning? Or is it a function that can only be imagined to be available introspectively to the computer? If the former, computers can do that now. If the latter, we have a genuine problem for physicalism.

Well, the premise is that humans are thinking machines. If a human could only output sentences in the way modern computers can, we would certainly begin to doubt that human were truly conscious or understood the meaning of the sentences he was generating. What we expect of a conscious, understanding person is that they behave as if they are inventing theories that explain their environment and correspondingly guide their actions. Today, computers can only do this at the level of insects. Modern computers are a million times slower than human brains. So, it's not just a case of something "imagined to be available introspectively to the computer." It's a fairly well-defined computing function.

The discussion is getting pretty far afield with regard to propositions, so I'll try not to drag it out.

>True, but the first proposition refers to a model that is consistent with your second proposition. It does not refer to anything beyond the model and its consequences.<

Say if you will that the proposition is a mental or virtual model, but don't conflate the model with its "consequences." You distinguish the two in the sentence above, so they can be distinguished. The "model" is one thing, its logical implications are another. And I would even say that the implications themselves are further virtual models. I suppose this is involves an attempt to identify a proposition with a physical state or set of physical events, upon which point we apparently must agree to disagree.

>Rather, the belief is that the world of experience is described by natural laws or regularities. Mathematics is just such a regularity.<

No, math (at least in terms of simple mathematical operations) consists of necessary truths, not just regularities. It is necessarily true that 1+1=2. I can see in my mind that it must be the case, irrespective of time or circumstance, in this or any world. I do not know its true by virtue of repeated observation that one object plus another object happens to equal two objects. The fact that objects attract one another in proportion to their masses is not necessarily true, not logically necessary. It is possible to imagine a world in which gravity operated differently, or not at all, while it is not possible to imagine a world in which 1+1=3. This was pointed out by Hume centuries ago and is still generally accepted in philosophical circles, including philosophy of science. One of the puzzles Hume never addressed is as follows: If physical causes and effects are not logically necessary and yet my thoughts are just instances of physical cause and effect, how can logical necessity play a role in my thoughts?

It is through my senses that I learn about cause and effect. Objects push or pull one another. They impart heat to one another, etc. These concepts are based in sensory experience. But one thought does not pull or push another thought, or impart angular momentum to it, or transfer heat to it. Such concepts are simply not applicable to sequences of thought, including logical thought, even though logical thought in our cases at least is dependent upon certain causes and effects in the brain as enabling conditions. Thought transcends physical cause-effect categories.

>Mathematics does not reduce to physics, but that doesn't make mathematics supernatural. It may make it non-physical, but that's not a useful distinction, IMO.<

It is useful if we are exploring the idea that all of reality reduces to physics, isn't it?

"One of the puzzles Hume never addressed is as follows: If physical causes and effects are not logically necessary and yet my thoughts are just instances of physical cause and effect, how can logical necessity play a role in my thoughts?"

Maybe he didn't because there is no puzzle here, unless one conflates the ability to think with the object of one's thinking, which you seem to be doing here.

"It is useful if we are exploring the idea that all of reality reduces to physics, isn't it?"

If that were true there would be no need for chemistry or biology or psychology or sociology, etc. There is no need for a naturalist to adopt such a nonsensical view.

>Maybe he didn't because there is no puzzle here, unless one conflates the ability to think with the object of one's thinking, which you seem to be doing here.<

No, it is naturalism that conflates the object of thinking with thinking itself by itdentifying the thought process as an instance of the causal processes that we observe in nature.

>If that were true there would be no need for chemistry or biology or psychology or sociology, etc. There is no need for a naturalist to adopt such a nonsensical view.<

What view? The view that the phemonena addressed by chemistry and biology can be reduced to physics? I think there are many naturalists--those who espouse reductive materialism--who would argue with you there. To say that the objects of those sciences are subsumed under physical laws is not to say that the physical laws may not be usefully summarized in the languages of special sciences. To say that the laws of optics or aerodynamics, for example, are useful is hardly to claim that they are not reducible under the standard model of physics.

"No, it is naturalism that conflates the object of thinking with thinking itself by itdentifying the thought process as an instance of the causal processes that we observe in nature."

Not at all. 'Thought process' is simply another term for thinking so lets replace it with 'thinking' in your statement above: "It is naturalism that conflates the object of thinking with thinking itself by identifying thinking as an instance of the causal processes that we observe in nature"

I see no conflation on the part of naturalism. I'm somewhat mystified that you do??

The fact that the brain is a causal mechanism does not prevent if from thinking about any number of things: even logically necessary things.

"What view?"

The view that everything can be explained by reducing it to the level of physics. I'm sure there are naturalists who think such a reduction possible, but there are other well-respected naturalists like E. Mayr and Bernard Williams who strongly disagree with that view.

This isn't quite correct. The theorems that follow from axioms are necessarily true given the axioms. But the axioms themselves are not inherently true. That's why we can have contradictory mathematical systems (e.g., different geometries, or two alebra problems with differently declared values of x) without any of the mathematics being wrong. Mathematics is an exploration of the possible axiomatic systems we can build, and the necessary theorems/consequences of those contingent choices of axioms.

If physical causes and effects are not logically necessary and yet my thoughts are just instances of physical cause and effect, how can logical necessity play a role in my thoughts?

I agree with anon - I don't see a problem here. We just have to be sure we are defining terms correctly. How do we define logical necessity? Something is logically necessary if it is a deductive theorem following from a set of axioms/definitions. We know that machines can do these sorts of computations. In other words, logical necessity isn't "out there." Logical necessity is a label we apply to results that are computed in a particular fashion.

But one thought does not pull or push another thought, or impart angular momentum to it, or transfer heat to it.

Thoughts most definitely do interact, and in fairly consistent ways. Thoughts trigger other thoughts by association.

Obviously heat and angular momentum are not carried by thoughts per se. That's because a single thought has no fixed thermal energy or angular momentum. A thought in a physical substrate will have a time-dependent energy density, so it will not have, say, a characteristic momentum.

A good analogy is the Pacific Ocean. The ocean has currents in it that have momentum. Yet we don't need to redraw the boundary of the pacific every day. The thing we call the Pacific is a physical arrangement of molecules with thermal energy and momentum, yet that thing is not charcaterized by those physical values. It's characterized by spatial extent.

Another analogy: your web browser does not impart heat or angular momentum to your word processor. This despite the fact that the low-level operation of these programs is very much concerned with energy and momentum.

Such concepts are simply not applicable to sequences of thought, including logical thought, even though logical thought in our cases at least is dependent upon certain causes and effects in the brain as enabling conditions. Thought transcends physical cause-effect categories.

I think you would accept that a computer could be programmed to explore the laws of physics by building predictive models of phenomena. It could also be programmed to devise new and interesting mathematical systems by devising axioms and proving corresponding theorems. So, there must be a causal link between computation using physical machines and mathematical theorems.

Well, I disagree that different geometries are "contradictory" in a way that imperils logical necessity, but at least we have logical necessity on the map. That's some progress.

>The thing we call the Pacific is a physical arrangement of molecules with thermal energy and momentum, yet that thing is not charcaterized by those physical values. It's characterized by spatial extent.<

The Pacific Ocean is characterized only by spatial extent and not by the water and its dynamic physical properties? That's a hard sell. Likewise, my browser is ultimately comprised of electrons traveling paths consistent with the formulations of QED, in which angular momentum plays an undisputed part.

>Thoughts most definitely do interact, and in fairly consistent ways. Thoughts trigger other thoughts by association.<

Obviously true, but the triggering of one thought by another by association may be conceived as just an overlay on physical causation. If it is apparently non-causal in physical terms, that appearance can be construed as illusory. But if the causing of one thought by another through logical inference is construed as illusion, we have refuted our power of reason--which is incoherent.

>We know that machines can do these sorts of computations. In other words, logical necessity isn't "out there." Logical necessity is a label we apply to results that are computed in a particular fashion.<

Machines can compute, but can they see that what they compute is logically necessary? You can see in your mind that it is necessarily true that 1+1=2 (throw in the required axioms if you need them). Now, can a computer likewise "see" that this computation is necessarily true? We can program a computer to yield 1+1=3, right? But that cannot mean that the computer "sees" that 1+1=3 the same way that you see that one plus one must equal--can only equal--two. No one can see that it is logically necessary that 1+1=3, not even a computer. In other words, we cannot equate output with introspective recognition, with "seeing" logical truths.

>I think you would accept that a computer could be programmed to explore the laws of physics by building predictive models of phenomena. It could also be programmed to devise new and interesting mathematical systems by devising axioms and proving corresponding theorems. So, there must be a causal link between computation using physical machines and mathematical theorems.<

Sure, the causal link is the alignment between the unthinking operations of the computer and our own thoughtful reflections. To illustrate, the simplest digital device is the abacus. Beads on wires. I can align the positions of beads on wires through representation so that mathematical values are yielded. The physical states of the abacus become pegs on which I can hang mathematical transformations for my own minded purpose. But beads on wires are not literally numbers. Moving beads on wires is not literally moving numbers back and forth. The abacus as a physical object or set of events does not perceive anything whatsoever about math. The same is true in principle if we automate the abacus with electricity. It remains true no matter how complex the representational manipulation becomes. Physically, computation is just manipulation of representations--NOT manipulation of what the representations refer to. Our minds supply the referents of the representations.

If you examine any two things you can find both similarities and differences. The organ known as the human brain (such as scientific experts presently know and examine it under their microscopes and via physical experiments), is of course different from the fullness of the mental world of our minds that we each experience. (But then, dissecting anything, like a frog, doesn't give you the fullness of that frog or its inner world either.)

Also, I agree with you that the connections linking our thoughts in long chains do not appear to be of the same kind of connections linking, say, actual metal chains. (However, we do know that the human brain like all other brains in nature features endless chain reactions of an electro-chemical sort. And the pathways of such electro-chemical activity are becoming more well known to scientists who are mapping them out.)

Question: If one is a "substance dualist" and believes that mental reasoning abilities are supernatural and enter the brain from outside the natural world, which part of the brain picks up these invisible signals from the supernatural world? In other words, if supernatural signals enter the brain at some point, what is that point? Or, if supernatural signals enter the brain at multiple points, then why can't both halves of a split-brain patient's brain "know" what the other half is thinking? Why can't one half of a split-brain patient "read the mind" of the other half of that same individual's brain? Why do split-brain patients, during such experiments, appear as if they were carrying on two separate thoughts and willing two different decisions at the same time?

Also, why the endless chain reactions of an electro-chemical sort that continue unabated between neurons and between entire sectors of the brain, traveling from one sector of the brain to the other and back again if the brain is being directed not by those reactions but by a supernatural force that is able to enter the brain and direct multiple brain sectors simultaneously?

Take the idea that there are more than three spatial dimensions. I might ask, "If there are fourth and fifth spatial dimensions tacked onto our three dimensions, at what point are they connected? Where exactly is the seam between the third and fourth dimensions, for example? Why can't I see these hypothetical dimensions? If they are real, they must have effects on the three dimensions that I live in, so why can't I see these effects?" However, it is in the nature of the concept of extra spatial dimensions that these questions don't have answers--or at least don't have the kind of answers we think we ought to get when we pose the questions. As I understand it (and I certainly don't pretend to understand it in technical terms) the reason many physicists propose extra spatial dimensions is not because they can picture them but because certain math equations related to particle physics do not yield rational answers unless extra dimensions are plugged into them.

Now, I am NOT invoking extra dimensions as part of an argument from reason. I am using them to illustrate that because straightforward answers, grounded in sensory experience, are not available to questions such as you pose does not mean that the concept that prompted them must be bogus. In the case of reason, denying a fundamental status for rationality does not yield disastrous mathematical results but disastrous logical results. We have to accept such a fundamental status to avoid incoherence. But talk of mental "substance" is a kind of metaphor, of course, because if substance in the ordinary sense were being proposed we would be right back at the starting point again.

I am saying that the interaction between mental and physical cannot universally be conceived of as physical cause-effect. If we could oberve a physical effect with a mental cause, it would consist of a an effect without a sufficient physical cause. The mental cause could be experienced but not observed through the senses. To say that we might observe a physical effect for which no sufficient physical cause is observable is strange but not irrational. We have just such a thing proposed in QM, don't we? Now, I'm not identifying the insufficiency of physical causes in the case of QM events with that of mental events. I am only invoking QM events to show that such a thing as physical effects for which physical causes are insufficient is not inconceivable. Actually, this fact was demonstrated by Hume before QM even came along.

What I'm questioning is how your earlier assertion that the mental is only metaphorically some kind of substance distinct from the physical can be coherently reconciled with your present assertain that the mental interacts with the physical. Sorry but I can't imagine a metaphor being able to interact with any kind of physical object.:-) I don't see how the possibility of a physical effect occuring without a known cause can be of help to you here because you are still postulating some kind of cause.

I was under the impression from your earlier remark that you recognized that identifying the mind with some kind of mental stuff has all the same difficulties that can be found with identifying it with the brain. Dualism has the added difficulty of then accounting for the interaction that takes place.

For a different understanding on modern science's impact on the causal closure theory you could take a look at the article by D. Papineau in the online Stanford Encylopedia of Philosopy:site

He gives a nice brief history of moderns science's view of what can cause physical effects. A much more detailed exposition is to be found in his book: Thinking About Consciousness.

Also thought I'd add one small snippet from the article:"Sometimes it is suggested that the indeterminism of modern quantum mechanics creates room for sui generis non-physical causes to influence the physical world. However, even if quantum mechanics implies that some physical effects are themselves undetermined, it provides no reason to doubt a quantum version of the causal closure thesis, to the effect that the chances of those effects are fully fixed by prior physical circumstances. And this alone is enough to rule out sui generis non-physical causes. For such sui generis causes, if they are to be genuinely efficiacious, must presumably make an independent difference to the chances of physical effects, and this in itself would be inconsistent with the quantum causal closure claim that such chances are already fixed by prior physical circumstances. Once more, it seems that anything that makes a difference to the physical realm must itself be physical."

Various aspects of the General Theory of Relativity cannot be pictured, so we use metaphors. The distortion of space-time by mass is often illustrated by the image of a bowling ball on a mattress. The directional perturbance of space-time by a moving mass may be pictured as an object moving through a viscous liquid. These images are metaphors to the extent that they allow us to form mental pictures of realities that otherwise cannot be pictured. That does not mean that the phenomena they represent are unreal.

The metaphor of "mental substance" is useful insofar as it claims causal efficacy for the mental, but it ought not to be interpreted as turning the mental into a physical substance. All metaphors have limits and will mislead if pushed too hard.

>I don't see how the possibility of a physical effect occuring without a known cause can be of help to you here because you are still postulating some kind of cause.<

I explicitly stated that I do not invoke QM as a means by which the mental works (Papineau has a valid point in that respect), but rather to demonstrate that physical events occurring in the absence of sufficient physical causes is not inconceivable. When you refer to "known cause" perhaps you miss the point that QM repudiates "hidden" causes in the form of physical variables that account particularly for quantum events. One U235 atom decays the next minute while another decays a year from now. It is not the case that there is an unknown physical cause of the difference in decay times. QM says that in principle there is no such physical cause.

"And this alone is enough to rule out sui generis non-physical causes. For such sui generis causes, if they are to be genuinely efficiacious, must presumably make an independent difference to the chances of physical effects, and this in itself would be inconsistent with the quantum causal closure claim that such chances are already fixed by prior physical circumstances. Once more, it seems that anything that makes a difference to the physical realm must itself be physical."

Outside the question of whether QM events are to be identified with mental events (no, they are not) the above remark is irrelevant. If we look around for causes and effects with the senses we are bound to find--surprise!--only causes and effects that can be found with the senses. Mental causes are reached by introspective experience, not by the senses--otherwise they would not be mental

QM can be of more illustrative help here, however. The reason for QM being widely adopted is that experimental results presented physicists with a difficult choice. They could admit that not all physical effects have the physical causes that a mechanical physical model demands, or they could question something more fundamental such as the sufficiency of numerical values to represent physical quantities. Understandably, they chose to preserve the link between physical and mathematical values because without it all science is threatened.

The AfR, if successful, proposes that there is nothing in the physical structures and processes of the brain that can conceivably be identified as a logical ground that leads to a logical consequent. If this argument holds, we have a choice between admitting that physical brain models are in principle incomplete with respect to rational thought or else invalidate our own reasoning. Choosing the first option requires us to give some fundamental, distinctive status to the mental to fill out the picture. However, that in turn presents us with a further choice.

We can give fundamental status to the mental but isolate it from the physical. Mental states then become epiphenomenal with regard to behavior, running in parallel with computation. The alternative is to brave the perils of interactionism. The AfR itself cannot help us with this choice. Personally, I think that ephiphenomenalism leads to a kind of conceptual incoherence different than that picked out by the AfR. The best argument against it is an appeal to the conservation of energy. But I disagree with Papineau on the size of this obstacle. To me, there is no conceptual problem posed by conservation of energy to compare with the one that infects ephiphenomenalism.

"The metaphor of "mental substance" is useful insofar as it claims causal efficacy for the mental, but it ought not to be interpreted as turning the mental into a physical substance. All metaphors have limits and will mislead if pushed too hard."

I'm sorry but you are the one claiming that this mental substance actually interacts with the physical realm. So 'mental substance' is not merely a metaphor - there has to be something that is actually impinging upon the physical realm that causes physical effects.

">I don't see how the possibility of a physical effect occurring without a known cause can be of help to you here because you are still postulating some kind of cause.<

I explicitly stated that I do not invoke QM as a means by which the mental works (Papineau has a valid point in that respect), but rather to demonstrate that physical events occurring in the absence of sufficient physical causes is not inconceivable. When you refer to "known cause" perhaps you miss the point that QM repudiates "hidden" causes in the form of physical variables that account particularly for quantum events. One U235 atom decays the next minute while another decays a year from now. It is not the case that there is an unknown physical cause of the difference in decay times. QM says that in principle there is no such physical cause."

Perhaps I have missed the point here. Or I didn't explain myself well enough. I'll try and restate it. You are positing a cause: saying that the mental is causing changes in the brain. Sure, it is conceivable that physical effects can occur without physical causes. Not only is it conceivable, but it was considered to be possible under Newtonian physics, as Papineau points out. But with the development of physics and, even more importantly of the study of physiology, the causal closure thesis turns what is conceivable into the impossible. Papineau explains why your reference to QM does not allow you to escape the causal closure thesis: the probability of any event is fixed by prior physical circumstances. This leaves no room for mental causation - unless that causation is also classified as physical.It's interesting that most of these discussions lead to rather endless debates over QM. I agree with Papineau here that it is more likely the maturation of the science of physiology (coupled with technological advancements like the micron microscope) that really puts the nail into the coffin of a dualistic model of mental causation.

""And this alone is enough to rule out sui generis non-physical causes. For such sui generis causes, if they are to be genuinely efficacious, must presumably make an independent difference to the chances of physical effects, and this in itself would be inconsistent with the quantum causal closure claim that such chances are already fixed by prior physical circumstances. Once more, it seems that anything that makes a difference to the physical realm must itself be physical."

Outside the question of whether QM events are to be identified with mental events (no, they are not) the above remark is irrelevant. "

The important point is not that QM events are to be identified with mental events, but the causal closure thesis still stands under QM.

"If we look around for causes and effects with the senses we are bound to find--surprise!--only causes and effects that can be found with the senses. Mental causes are reached by introspective experience, not by the senses--otherwise they would not be mental."

I believe this to be incorrect. If we see a physical event and it is not possible to attribute that event to a physical cause then we would have empirical evidence to support something like mental causation. The fact that we have to use our senses to help us find causes and effects does not a priori limit us to finding only physical causes to physical effects. As has already been pointed out, Newtonian physics left room for non-physical causes.

"The AfR, if successful, proposes that there is nothing in the physical structures and processes of the brain that can conceivably be identified as a logical ground that leads to a logical consequent."

Relying on what is "conceivable" as a tool to determining ontological matters seems to me to be a very shaky methodology. I don't personally have much trouble conceiving of the brain being organized in such a manner that it can produce validly logical results. The computer analogy demonstrates that there is no inherent incompatibility between a physical causal system and rational reasoning. You seem to misunderstand that analogy by pointing to the fact that the computer is not aware of the logical steps it is going through. But awareness or self-consciousness is irrelevant here. What is relevant is that the instructions for engaging in logical operations can be encoded on the hardware of the computer in order that the logical operations can be carried out by a physical causal system. Awareness or self-consciousness is a separate matter from logical processes. Unless you conflate the mental with the logical, which you still seem to me to be doing.

"If this argument holds, we have a choice between admitting that physical brain models are in principle incomplete with respect to rational thought or else invalidate our own reasoning. Choosing the first option requires us to give some fundamental, distinctive status to the mental to fill out the picture. However, that in turn presents us with a further choice.

We can give fundamental status to the mental but isolate it from the physical. Mental states then become epiphenomenal with regard to behavior, running in parallel with computation. The alternative is to brave the perils of interactionism. The AfR itself cannot help us with this choice. Personally, I think that epiphenomenalism leads to a kind of conceptual incoherence different than that picked out by the AfR. The best argument against it is an appeal to the conservation of energy. But I disagree with Papineau on the size of this obstacle. To me, there is no conceptual problem posed by conservation of energy to compare with the one that infects epiphenomenalism. "

Perhaps interactionism is more coherent than epiphenomenalism. That alone doesn't qualify it as a theory worthy of serious consideration. The best science we have so far supports the causal closure thesis, that alone is enough to disqualify interactionism as a likely theory.

I'm with darek here. I think anon is missing something in the logic/mental distinction.

I agree that computers and calculators can instantiate states which represent chains of logically related statements, and that these states can be causally related.

Several questions can be raised at this point.(1) Is this sufficient to amount to reasoning?(2) How likely is such representation and causal relation is humans given evolutionary naturalism?(3) What, at a meta-level, makes it the case that certain representations are related validly and others related invalidly?

On (1) Victor has pointed out that the mental states need to cause one another in virtue of what they represent and in virtue of the logical relationship between the representations and in virtue of awareness of that relationship. There are Carollian (Lewis Carroll on Archilles and the Tortoise) infinite regresses in the area which make it difficult to go the route which Anon is attempting to go. This higher level awareness, when modelled as another mental state representing a logical relation between other representations may be causally sufficient for the "effect" representions to become instantiated, but thinking of the awareness in this way leads to the Carrollian regresses. After all, don't we also need to be aware of the awareness of the logical relationship in which the awareness stands to the lower level representations? And Also aware of the awareness of the awareness ...

On (2) the question is whether evolution makes likely that we'd have cognitive faculties and inference patterns which are generally reliable and in accordance with deductive and inductive logic. For reasons that Plantinga has explained well, it's not at all obvious that this would be likely. So even if naturalistically possible, reason and knowledge may disconfirm naturalism. See also my long exchange with Darek and Jason on evolutionary explanations. I'm not very good at adding links ... perhaps someone else could do that?

On (3) as Darek has already pointed out a computer can be made to instantiate invalid reasoning processes too. Since this is the case, there must be some standard of "logic" external to the representations, accordance which which makes certain causal relations instances of valid reasoning, and discordance with which makes them instances of invalid reasoning. What exactly is this external standard? Can it be accounted for naturalistically? Any account must capture both the objectivity and prescriptivity of logic. It's not obvious what a naturalistic account would look like. But again, any account we give here will need to be consistent with our answer to (1). Remember that awareness (i.e. some sort of interaction with) the standards of logic has to play a role in explaing why we think as we do.

In short, the mere appeal to the calcuator and computer will not do. The only reason we trust the calcuator is that it has been designed to function in accord with logic. It does this with no awareness of what it does. Something with awareness could possibily direct its own thoughts towards validity without the underlying causal processes being designed, but without awareness design looks necessary. You could pin your hopes on evolutionary "design" but that seems unlikely and even then you'd have a mere simulation of reasoning not real reasoning (see that discussion I didn't link to above).

>Papineau explains why your reference to QM does not allow you to escape the causal closure thesis: the probability of any event is fixed by prior physical circumstances. This leaves no room for mental causation - unless that causation is also classified as physical.<

You have to decide whether you (and presumably Papineau) are defining nonphysical mental causes out of existence, or arguing that they probably don't exist because we have not observed them. If you simply want to define anything that has a physical effect as physical, then the term physical doesn't have much value--unless you provide other properties that necessarily go along with causal efficacy such as spatial extent or an essentially nonpurposive character. To generalize instead that we do not observe physical effects whose probability is not conditioned by prior physical circumstances is hardly conclusive against their occurrence in rational thought or volition. The place we have to look for these effects is in the most complex integrated system known to man, the human brain. The complexity of events in the brain is so great that ruling out all anomalies at every level of operation is beyond current neuroscience to establish. The brain's complexity may pose a chaotic barrier that cannot be breached even in theory.

>Relying on what is "conceivable" as a tool to determining ontological matters seems to me to be a very shaky methodology.<

Well, it depends on the particulars. If someone says they cannot conceive of a fourth spatial dimension, we can point out that our cognitive limitations ought not to lead us to rule out the concept. But say that someone says that they have the number two in a box on their coffee table. We ask them if they mean a representation of the number two and they insist that, no, they have the number two itself in the box. I can object validly, I think, that such a thing is simply inconceivable.

>You seem to misunderstand that analogy by pointing to the fact that the computer is not aware of the logical steps it is going through. But awareness or self-consciousness is irrelevant here. What is relevant is that the instructions for engaging in logical operations can be encoded on the hardware of the computer in order that the logical operations can be carried out by a physical causal system.<

It can hardly be irrelevant that something goes on in the mind that does not go on in the computer. Take the following statements:

(1) The computer gave the answer it did because the answer was logical.

(2) The student gave the answer she did because she saw that the answer was logical.

Is there are real difference between 1 and 2? Does this real difference entail a physical difference? If it is a real difference but does not entail a physical difference, we have epiphenomenalism; if it is a real difference that entails a physical difference then we have some kind of interaction between mental and physical.

It may be useful to apply "logic" to mechanical operations such as the manipulation of representations by a computer. Nevertheless, if there is a subspecies of logic in which the conscious perception of logical grounds plays an indispensible role, then an explanation is required for the character of this subcategory.

One needs to be careful in their use of language. If you mean in (2) that the student literally saw the answer then obviously there would be a physical difference. However, I see no interaction here between two ontologically distinct substances: the mental and the physical, since the act of seeing is well grounded in the physcial. But I find it hard to believe you really mean it literally here.

You keep talking about the mind perceiving logical relations or mental objectst as though “perception” is an accurate way to describe these “mental actions.” Looks to me like you may be making a fundamental error here. At the least, you are doing quite a lot of question-begging.

Certainly we can agree that the student is aware of the fact that her answer is a logical one. But that doesn’t mean that she percieves or sees the logical relationship here. I’d be interested in learning your case for such mental perception.

>You keep talking about the mind perceiving logical relations or mental objectst as though “perception” is an accurate way to describe these “mental actions.” Looks to me like you may be making a fundamental error here. At the least, you are doing quite a lot of question-begging.<

Well, I admit that I was not using the word "see" in a literal sense, nor did I believe there was much chance of someone taking it that way. Distinguishing between perception of a logical relation and awareness of one seems like hair-splitting, but OK, I'll rephrase the last part of my last post:

It can hardly be irrelevant that something goes on in the mind that does not go on in the computer. Take the following statements:

(1) The computer gave the answer it did because the answer was logical.

(2) The student gave the answer she did because she was aware that the answer was logical.

Is there a real difference between 1 and 2? I think there is, because we can distinguish between them. Notice that the difference has a causal aspect. For the first case to obtain, the computer need not understand the meanings of representations--the physical properties of the representations are causally sufficient to explain the computer's output. For the second case to obtain, the student must understand the meanings of the representations that constitute the question and the answer. That is, meanings must play some causal role in order for the student to be aware of logical relationships. But there is no physical state or event in the brain of the student that we can possibly identify as the meaning of a representation as opposed to a representation.

Sad, really, the original comment from Loftus is actually intelligent, well-articulated, and interesting. WTF happened to that guy? Like Dembski, who started with some fairly interesting things, became something of a demagogue.

About Me

I am the author of C. S. Lewis's Dangerous Idea: In Defense of the Argument from Reason, published by Inter-Varsity Press. I received a Ph.D in philosophy from the University of Illinois at Urbana-Champaign in 1989.